It is known for pubs and the like to store beer in kegs. The kegs are supplied with gas, typically carbon dioxide or nitrogen or a combination of the two, to maintain a desired pressure in the keg. The pressure within the keg helps to drive the beer to the dispensing tap where the beer is served, and also serves to maintain carbonation in the beer. The composition of gas and pressure used depends upon the pressure required by the particular beer in the keg.
As beer is used up, more gas needs to be pumped into the keg to maintain the required pressure. Typically, once a keg has been fully used up and no longer contains any beer, the keg is removed from the beer supply line and returned to the brewery where residual gas is then vented.
Accordingly, large amounts of gas, particularly carbon dioxide, are required within a beer dispensing system to provide the necessary pressure to the kegs. The greater the number of kegs within the system the greater the amount of gas required.
Typically the gas is stored in tanks which are delivered to the pub or like establishment, and once the tanks are emptied they are returned to the gas provider to be re-filled. Since the gas used by the kegs is usually vented to atmosphere, new deliveries of gas have to be made frequently.
This has a negative impact on the environment, not only because of the carbon dioxide which is directly vented to the atmosphere from the used kegs, but also because of the emissions from the delivery trucks which need to make frequent deliveries.
Accordingly there is a need for a system that can reduce the gas wastage of beverage dispensing systems.
A system that attempts to achieve this is shown in WO 01/94252 (Jones), which shows two embodiments of a gas reclamation system for a beverage dispensing system.
In the first embodiment, gas from a used keg is passed through a separator which separates the gas before passing the separated gas into a collection tank. The separated gas is then passed through a compressor after which it may be re-used by the system.
There are several drawbacks with having the compressor at the last stage as shown in this embodiment of the system. First, having the gas collection tank positioned upstream of the compressor means that only a portion of the gas in the keg will be recoverable, this portion being equal to the balanced pressure between the collection tank and the keg.
To increase the amount of gas recoverable from the keg, the compressor will have to be stopped and started frequently to ensure a pressure differential exists between the keg and the collection tank. This causes very high wear on the compressor which will therefore need to be maintained frequently.
Secondly, in the first embodiment the separator is shown upstream of the compressor. Therefore the gas will pass through the separator at a pressure no greater than the maximum top pressure of the keg, which is typically about 375 kPa (all pressures quoted are absolute pressures). This pressure is not sufficient to ensure complete separation of carbon dioxide and nitrogen from a gas blend mix, since pressures of more than about 500 kPa are typically required to ensure separation when using a gas separation filter.
The second embodiment of the Jones system uses a gas sensor to sense the composition of the gas being reclaimed from the used keg, before passing this gas through a compressor and into a relevant collection tank for that particular composition of gas.
A major drawback of this embodiment is the number of collection tanks that are required i.e. one collection tank per type of gas mix recovered. So if an establishment has a number of different types of beer within the dispensing system each requiring a different gas blend mix, then this same number of storage tanks will be required.
Another major drawback of both embodiments of the Jones system is that it requires a user to disconnect the keg from the beer supply before connecting it to the gas reclamation system. This increases the amount of labour and therefore costs associated with using the system.
It is therefore an object of the present invention to overcome or at least mitigate these and other problems in the prior art.